The first hand-held indirect ophthalmoscopy lens which was used as a condensing and image-forming lens, was spherical and of low power, +13.00 diopters. The aerial image produced with this spherical lens was magnified, inverted, and quite blurred towards the periphery. In 1958, Sudarsky and Volk in their paper entitled "Aspherical Objective Lens As an Aid in Indirect Ophthalmoscopy", American Journal of Ophthalmology, Vol. 46, No. 4, April 1959, described their preliminary results using aspheric condensing-image forming lenses for indirect ophthalmoscopy.
In my copending U.S. patent application, "Lens for Indirect Ophthalmoscopy", Ser. No. 437,279, filed Oct. 28, 1982, the lens is designed with two different conoid surfaces, with the aerial image of the fundus almost entirely aberration-free. In my copending patent application "Indirect Ophthalmoscopy Lens for Use with Slit Lamp Biomicroscope", Ser. No. 727,764, now U.S. Pat. No. 4,627,694 filed May 1, 1985, the indirect ophthalmoscopy lens for use with the slit lamp biomicroscope is a symmetrical double aspheric very high powered lens, with nominal dioptric powers ranging from 60 diopters to 130 diopters. With all of the prior art indirect ophthalmoscopy lens, the aerial image produced is inverted. The novel optical system of this invention produces an upright clear aerial image of the fundus which is viewed with the indirect ophthalmoscope and with the slit lamp biomicroscope.